Definition: A beyond-use date (BUD) is the date after which a compounded or opened medicine should not be used. It is set by the pharmacy or by a standard such as USP chapter 797, and it is usually much shorter than the manufacturer's expiration date. CDC says a BUD should never go past the original expiration date.
BUD vs expiration date
An expiration date is set by the manufacturer for an unopened product stored as directed. A BUD is shorter. It accounts for what happens after the product is mixed, repackaged or opened, when germs can get in and the medicine may break down faster.
For opened multi-dose vials, CDC cites USP chapter 797: date the vial and discard it within 28 days unless the manufacturer states another date. CDC also says the BUD should never exceed the manufacturer's original expiration date. FDA notes that compounded drugs are not FDA approved and are not reviewed by FDA for safety, effectiveness or quality before they are sold, so the BUD on a compounded vial is the pharmacy's own call.
Worked example
Counting 28 days
- You first open a multi-dose vial on October 3.
- October 3 + 28 days = October 31.
- If the printed expiration date is October 20, the earlier date wins: discard by October 20.
Why it matters when you track doses
Two dates live on one vial: the label date and the date you opened or mixed it. The second one is easy to forget. Write it on the vial and in your log the day you first use it.
- Pens have their own in-use limits. The Wegovy FlexTouch pen can be used for up to 56 days after first use, per its label. That is a tested product limit, not a BUD for a compounded vial.
- Mixed peptides are different again. Research peptides have no label and usually no published stability data after mixing.
Read more on Dose Track: How long mixed peptides last · Peptide storage guides
General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Is a beyond-use date the same as an expiration date?+
No. The expiration date is set by the manufacturer for the unopened product. A BUD is a shorter limit that applies after compounding or opening, and CDC says it should never go past the expiration date.
What BUD applies to an opened multi-dose vial?+
CDC, citing USP chapter 797, says 28 days after opening unless the manufacturer states another date.
Which date do I follow if both are on the vial?+
Whichever comes first. A BUD should never extend past the original expiration date.